An Introduction to Information Processing

By Harvey M. Dietel and Barbara Deitel

An Introduction to Information Processing provides an informal introduction to the computer field. This book introduces computer hardware, which is the actual computing equipment. Organized into three parts encompassing 12 chapters, this book begins with an overview of the evolution of personal computing and includes detailed case studies on two of the most essential personal computers for the 1980s, namely, the IBM Personal Computer and Apple's Macintosh. This text then traces the evolution of modern computing systems from the earliest mechanical calculating devices to microchips. Other chapters consider the components and operation of typical data communications systems. This book discusses as well the various types of communications networks and communications via space satellites. The final chapter deals with software or computer programs, the sets of instructions that programmers write to inform the computer how to solve particular problems. This book is a valuable resource for computer specialists, mathematicians, and computer programmers.

• Language: English
• Publisher: Academic Press
• Release date: Jun 28, 2014
• ISBN: 9781483214016

Book preview

AN INTRODUCTION TO INFORMATION PROCESSING

HARVEY M. DEITEL

Boston College

BARBARA DEITEL

ACADEMIC PRESS COLLEGE DIVISION

Orlando      San Diego      San Francisco      New York      London      Toronto      Montreal      Sydney      Tokyo      São Paulo

Table of Contents

Cover image

Title page

Copyright

Dedication

Preface

Part One: Introduction

Introduction to Introduction

Chapter 1: The Information Revolution

Publisher Summary

Introducing the Computer

The Benefits

The Dangers

Looking to the Future

An Introduction to Personal Computing

Summary

Important Terms

Self-Review Exercises

Discussion Questions

Projects

Chapter 2: The Evolution of Computers

Publisher Summary

Early Computing Devices

The Dawn of the Modern Computer Age

Summary

Important Terms

Self-Review Exercises

Discussion Questions

Project

Part Two: Hardware

Introduction to Hardware

Chapter 3: The Processor

Publisher Summary

The Basic Computer Processing Cycle

The Central Processing Unit

The Binary Number System

Data Organization

Machine Language Instructions

The Josephson Junction: The Computer on Ice

Consequences of Technology

Biochips (Fleshware?)

Summary

Important Terms

Self-Review Exercises

Discussion Questions

Project

Chapter 4: Input: Gateway to the Computer

Publisher Summary

Punched Cards

Key-to-Tape and Key-to-Disk Systems

Terminal-Oriented Systems

Touch Sensing

Other Input Devices

Source Data Automation

Summary

Important Terms

Self-Review Exercises

Discussion Questions

Projects

Chapter 5: Output: Getting Results from Computers

Printed Reports

Types of Printers

Terminal-Oriented Systems

Cathode Ray Tube Terminals

Portable Terminals

Other Types of Computer Output

Applications for the Future

Summary

Important Terms

Self-Review Exercises

Discussion Questions

Projects

Chapter 6: Secondary Storage

Publisher Summary

Magnetic Tape Storage

Disk Storage

Mass Storage Devices

Bubble Memory

Optical Disks

File Organization Methods

Applications for the Future

Summary

Important Terms

Self-Review Exercises

Discussion Questions

Projects

Chapter 7: Data Communications

Publisher Summary

History

How Data Communications Systems Work

Asynchronous and Synchronous Transmission

Data Transmission Codes

Simplex, Half-Duplex, and Full-Duplex Transmission

Line Speed

Transmission Media

Line Configuration

Data Communications Networks

Multiplexors

Concentrators

Common Carriers

Expectations for the Future

Summary

Important Terms

Self-Review Exercises

Discussion Questions

Projects

Part Three: Software

Introduction to Software

Chapter 8: Structured Programming

Publisher Summary

What Is a Computer Program?

The Program Development Process

Self-Review Exercises

Discussion Questions

Projects

Chapter 9: Programming Languages

Publisher Summary

Programming Languages

A Survey of High-Level Languages

Query Languages

A Universal Programming Language

Software Packages

Trends

A Brief Introduction to LOGO

Summary

Important Terms

Self-Review Exercises

Discussion Questions

Projects

Chapter 10: Structured Systems Analysis and Design; Systems Acquisition

Publisher Summary

Why Develop or Modify Systems?

The Systems Life Cycle

Systems Acquisition

Case Study: Structured Systems Analysis and Design

Summary

Important Terms

Self-Review Exercises

Discussion Questions

Projects

Chapter 11: Database Management Systems, Management Information Systems, Decision Support Systems

Data as a Business Resource

Database Management Systems

Management Information Systems

Decision Support Systems

Summary

Important Terms

Self-Review Exercises

Discussion Questions

Projects

Chapter 12: Operating Systems

Publisher Summary

Systems Programs

Applications Programs

Operating Systems

Operating Systems Functions

Batch Processing

Multiuser Operating Systems

Multiprogramming

Channels and Interrupts

Double Buffering

Storage Protection

Relocatable Programs

Reentrant Programs

Deadlock

Timesharing

Real-Time Systems

Scheduling

Print Spooling

Virtual Storage

Multiprocessing

Security

User-Friendliness

Firmware

Case Study 12-1 CP/M

Case Study 12-2 UNIX, XENIX, MS-DOS

Conclusion

Summary

Important Terms

Self-Review Exercises

Discussion Questions

Projects

Appendix A: BASIC Programming

Appendix B: Number Systems

Appendix C: The Computing Profession

Glossary

Trademarks

Illustration Credits

Index

Copyright

Illustration credits appear on page 445.

Trademarks appear on page 444.

Copyright © 1986 by Academic Press, Inc.

All rights reserved.

No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopy, recording, or any information storage and retrieval system, without permission in writing from the publisher.

Academic Press, Inc.

Orlando, Florida 32887

United Kingdom Edition Published by Academic Press, Inc.

(London) Ltd., 24/28 Oval Road, London NW1 7DX

ISBN: 0-12-209005-5

Library of Congress Catalog Card Number: 85-73035

Printed in the United States of America

Dedication

To our children, Paul and Abbey

Preface

An Introduction to Information Processing is the product of one of the most ambitious research, writing, and production efforts ever undertaken in computer science publishing. Our goals were clear: make the book exciting, complete, up-to-the-minute, innovative, and visually smashing; deal with controversial issues head on, and include humor and anecdotal asides for the reader’s enjoyment. The book contains one of the most dramatic and comprehensive graphics packages that has appeared in an introductory computer text.

The average person who reads this text is already well aware of the enormous impact computers are having on our personal lives and business enterprises. A familiarity with computers, how they work, and the kinds of applications they are used for is essential for living in today’s increasingly complex world. This text is designed for use in a one-semester college course that introduces the basic principles of computers; it meets or exceeds the guidelines of the major professional organizations for computer literacy courses taught by departments of computer science, management, data processing, information sciences, and others.

We enjoyed writing the book; it gave us an opportunity to immerse ourselves in the most current information available in the computer field. We have read thousands of articles and communicated with hundreds of companies, organizations, and government agencies. We have met hundreds of interesting people at computer trade shows and professional conferences throughout the country, and we have had the opportunity to work with some of the leading professionals in the publishing industry. We sincerely hope you’ll enjoy reading the book as well.

Features of the Text

We have loaded An Introduction to Information Processing with innovative materials in addition to presenting traditional basic computing concepts. We probe the reader’s mind with challenging questions. We attack controversial issues directly.

The pictures in the text were acquired from hundreds of companies, publishers, and photographers who gave us their enthusiastic cooperation. These photographs and illustrations bring the reader right into the environments where computers are being used; the vast majority of these pictures are supplied as transparencies and color slides for projection in the classroom.

We have included a number of carefully chosen cartoons and anecdotes; our goal is not so much to get fast laughs as to draw the reader’s attention to important issues these pieces raise. Consider them carefully; there is much food for thought here.

We have included numerous enrichment pieces that are highlighted against color backdrops. They supplement the text, but we strongly recommend their inclusion in the required readings for the course. Material in these pieces is included in the exercises.

A Tour of the Text

An Introduction to Information Processing is divided into three major sections and three appendices. Each section consists of several related chapters. Part One provides an informal introduction to the computer field. Chapter 1 presents some basic computing concepts and introduces personal computing.

The personal computer, made possible by the tiny and economical microprocessor, is reshaping the computer industry and our society as well. Now small businesses and individuals may have their own computers at their disposal 24 hours a day. Chapter 1 traces the evolution of personal computing and includes detailed case studies on two of the most important personal computers for the 1980s—the IBM Personal Computer and Apples Macintosh. The use of home computers in our daily lives is discussed: how they can help to save energy, plan nutritious meals, balance checkbooks, and maintain home budgets.

Chapter 2 traces the evolution of modern computing systems from the earliest mechanical calculating devices to today’s microchips. The history of the field is divided into four distinct generations, each defined by major innovations in electronics technology. The fifth generation, expected to appear about 1990, is discussed.

Part Two introduces computer hardware, the actual computing equipment. Chapter 3, The Processor, discusses the so-called brain of the computer. The chapter contains two special sections, one describing the manufacture of microprocessor computers and the other the logical operation of computers. It concludes with a discussion of biochips and how they make living computers possible.

The many ways in which data may be entered into computers is considered in Chapter 4, Input: Gateway to the Computer. Today we enter most information into computers on typewriterlike keyboards, but more user-friendly input methods are becoming popular, including touch sensing, in which the user simply touches a symbol on a display screen, and speech recognition, in which the computer recognizes spoken commands. Various input devices that automatically read markings on paper are also discussed.

Chapter 5, Output: Getting Results from the Computer examines how computers present their results, or outputs. The chapter considers the more popular types of printers that produce output on paper and focuses on laser printing, the printing technology of the future, in which intense beams of light are used to draw letters, digits, and even pictures. The operation of display screen terminals is discussed. Computerized speech generation, called speech synthesis, is explained in detail. The operation of computer output microfilm devices is considered, as is computer graphics, the computerized preparation and processing of pictures. The use of computers in the Shroud of Turin controversy is examined—bringing together the ancient and the modern.

Chapter 6, Secondary Storage, considers the storage and retrieval of massive amounts of computer-accessible information from secondary storage devices such as magnetic tape and magnetic disks. The operation of floppy disks and large-capacity Winchester disks, now so popular on personal computers, is discussed, and the relative speeds and capacities of these devices are compared. The chapter concludes with a discussion of the use of lasers with optical disks, one of the newer secondary storage technologies.

The movement of data between computer systems is examined in Chapter 7, Data Communications. The chapter covers the components and operation of typical data communications systems, the various types of communications networks, and communications via space satellites. It examines issues of security and privacy and discusses problems raised by the transmission of information across international borders. Once again the focus is on lasers in an in-depth discussion of fiber optics, the communications cable technology of the future in which beams of laser light are transmitted over glass wires.

Part Three deals with software, or computer programs, the sets of instructions that programmers write to inform the computer how to solve particular problems. Chapter 8, Structured Programming, presents a general discussion of program design principles. The discussion is independent of any particular programming language. Structured flowcharting and pseudocode, state-of-the-practice techniques that foster the development of high-quality computer programs, are explored. The chapter presents a detailed discussion of the chief programmer team concept that has proved so successful in the development of small- and medium-sized software systems. Nine case studies are included to illustrate the use of structured flowcharting and pseudocode in structured program development.

Chapter 9, Programming Languages, considers the various important programming languages that are commonly used. The chapter traces the evolution of programming languages from the tedious machine languages of the 1940s to the convenient English-like query languages of the 1980s. A survey of the most important and popular programming languages is presented, including BASIC (discussed in detail in Appendix A), FORTRAN, COBOL, PL/1, RPG, APL, Pascal, C, Ada, Forth, LISP, and LOGO.

Chapter 10, Structured Systems Analysis and Design discusses the development, installation, evaluation, and control of computer systems. The chapter is particularly relevant for people who are likely to develop their own computer-based systems or who work in organizations in which computer systems development is an ongoing activity. For others, several popular means of acquiring systems from various types of systems suppliers are discussed. The chapter ends with a detailed case study using the state-of-the-practice techniques of structured systems analysis and structured systems design to develop a computerized reservations system for a car rental agency.

Certain computer applications systems are particularly useful to businesses and organizations. Chapter 11, Database Management Systems, Decision Support Systems, and Management Information Systems, discusses these systems. Database management systems (DBMS) control the secure storage and accessing of the large amounts of information that businesses must process. The chapter discusses the major types of database management systems and includes a case study on the type receiving the most attention today—the relational DBMS. It also discusses management information systems (MIS), computerized systems that on a regular schedule provide managers with the information they need to perform their key tasks of planning, organizing, directing, and controlling. A detailed case study considers nine of the key computer systems that constitute a major portion of most management information systems. The chapter proceeds with a discussion of decision support systems (DSS), interactive computer-based systems that support management decision-making activities. They are especially useful in support of the planning function. Two particularly valuable case studies on DSS are included. The first introduces the notion of electronic worksheets—the most successful software products of all time and the ones that brought DSS systems to the attention of personal computer users. The second case study provides a detailed look at decision support in a typical business planning situation. A mathematical model of a business is created and solved in several interesting ways to yield useful information to support management decision making.

Operating systems are the software systems that manage the computer’s hardware and make it more friendly and usable to computer users. Chapter 12, Operating Systems, considers the functions and capabilities of such systems. It illustrates why multiuser operating systems are so much more complex than single-user systems. It briefly introduces some of today’s most popular personal computer operating systems, including the UNIX system developed by Bell Laboratories and the XENIX and MS-DOS systems developed by Microsoft. MS-DOS is supplied as PC-DOS with the IBM Personal Computer (often called simply the PC). A detailed case study on CP/M, a widely used personal computer operating system, is provided.

The book contains three appendices. Appendix A is a complete minicourse on the BASIC programming language. The discussion is carefully keyed to the case studies on structured programming in Chapter 8. After studying this appendix, the reader should be able to write and understand useful BASIC programs quickly and easily. To take maximum advantage of this portion of the text, the reader should have access to a computer system. All programs should be entered and tested on the computer. The Appendix is carefully divided into four modules. Module 1 presents an introduction to the language. Module 2 introduces the elements of structured programming in BASIC with six case studies covering decision making, looping, counting, totaling, averaging, and finding the largest of a series of numbers; the case studies parallel Case Studies 1 through 6 of Chapter 8. Module 3 presents the more substantial topics of single-subscripted arrays, subroutines, and program development with stubs and drivers; its three case studies parallel Cases 7 through 9 of Chapter 8. Module 4 presents a series of advanced case studies that examine the important topics of fancy print formatting, sorting, double-subscripted arrays, and using randomness to develop simulation programs.

Appendix B explains the principles of the various number systems that are useful in the study of computers, the most important of which is the binary number system, also called the base two number system, in which all numbers are expressed as combinations of zeros and ones.

Appendix C on the computing profession has been included for the reader considering a career in the field.

For the Student

We have included several features to help the student master the material. Each chapter begins with an attention-getting illustration, a statement of learning objectives, a chapter outline, and one or more thought-provoking quotations. Each chapter ends with a summary and an alphabetized list of important terms. Twenty self-review exercises—10 matching and 10 fill-in-the-blanks—are included; answers for these are provided to help the student evaluate his or her progress. Ten discussion questions are included to create material for homework and class discussions. Each chapter also includes one or more suggested projects. Many of these encourage the students to perform work outside the classroom—to investigate and experience the applications and implications of computers in the society around them.

A comprehensive Glossary includes definitions of 570 terms, 360 of which are highlighted in the Important Terms sections throughout the text. An especially thorough Index includes page references for the many terms that are highlighted in boldface type in the chapters.

Appendix C provides a wealth of information for people considering careers in the computer field or in closely related fields. It discusses many of the popular positions held by computing professionals, describes available educational programs, and lists the key professional organizations and certification programs. Perhaps the most valuable feature of the appendix is its presentation on how to go about searching for a job; the appendix describes how to prepare a résumé and cover letter and provides the names and addresses of more than 100 of the leading employers in the computer industry throughout the United States. College seniors should write to the personnel directors of these and other companies in the fall; many of them will send literature about careers they offer, their salary scales and benefits, and how to apply for jobs they offer.

For the Instructor

We have worked very hard to provide the instructor with valuable teaching materials to help make the classes interesting and enjoyable. We believe strongly in the value of graphics and illustrations, so we have assembled a large support package of slides and transparency masters. We have selected many illustrations from the text for the Transparency Masters, and we have chosen many pictures from the text for inclusion in the Color Slides Package. Thus, most of the art from the text is available for projection in the classroom.

We have prepared a Test Bank containing examination questions and answers for each of the chapters of the text. A Computerized Testing Service and Test Generation Software are available from the publisher. The Instructor’s Manual contains numerous teaching hints and provides answers to each of the discussion questions from the main text. With the exception of the Color Slides package, all this material is combined in one Instructor’s Resource Manual.

Acknowledgments

One of the pleasures of authorship is acknowledging the many people whose names may not appear on the cover but without whose efforts, cooperation, and encouragement a work of this scope could never have been completed.

We are fortunate to have been able to work with the extraordinary team of publishing professionals at Academic Press. These people had to work under the strain of tight deadlines and demanding authors to make this project happen; they did it with vigor, determination, and dedication.

Dale Brown, our computer science editor, provided many valuable suggestions that helped shape the final product, and he recruited and supervised a demanding and insightful team of reviewers. These people scrutinized every word, every illustration, and every aspect of the pedagogy of the text. They provided innumerable suggestions that helped refine the manuscript in ways we could never have achieved on our own. We are very pleased to acknowledge their efforts:

Darrell Abney, Nashville Technical Institute

Julian Andersen, Shoreline Community College

Russell Blankenfeld, Rochester Community College

Kolman Brand, Nassau Community College

Michael Capsuto, Cypress College

John Carroll, San Diego State University

Laura Cooper, College of Mainland

Van Cunningham, American Technical University

Wil Derschimer, Seminole Community College

Joe Evans, Southwest Missouri State College

Judie Gammage, El Centro College

Homer Gerber, University of Central Florida

Gilbert Ghez, Roosevelt University

Carla Hall, Florissant Valley Community College

Don Henderson, Western Kentucky University

Robert Lacey, Valencia Community College

Joseph McMenamin, Grossmont Community College

Stephen Mansfield, McHenry Community College

J Hayden Mathews, Murray State College

Amanda Meredith, Florida Junior College

Cathie Norris, North Texas State University

Curtis Rawson, Kirkwood Community College

Paul Ross, Millersville State University

Alan Schwartz, University of Missouri-St. Louis

Earl Talbert, Central Piedmont Community College

E M. Teagarden, Dakota State College

James R. Walters, Pikes Peak Community College

Judith Wilson, University of Cincinnati

David Whitney, San Francisco State University

We would also like to thank Fr. J. Donald Monan, S.J., President of Boston College; Fr. Joseph Fahey, S.J., Academic Vice President; Dean John Neuhauser of the School of Management; and Professors Peter Kugel, James Gips, Peter Olivieri, and Richard Maffei for their friendship and encouragement, and for creating an environment in which this writing effort could thrive.

We hope you’ll enjoy reading our text. We would greatly appreciate your comments and criticisms addressed to:

Harvey and Barbara Deitel

c/o Computer Science Editor

Academic Press, Inc.

Orlando, FL 32887

We will respond to all correspondence immediately.

Part One

Introduction

Outline

Introduction to Introduction

Chapter 1: The Information Revolution

Chapter 2: The Evolution of Computers

Introduction to Introduction

Computers are machines that process huge amounts of information at staggering speeds. Once understood and programmed correctly, computers can be used to make life more convenient, more enjoyable, and more rewarding. They can enrich every facet of life. They are fun to use and can help reduce tedious work. They can be used to improve the lives of disadvantaged and handicapped people, facilitate major breakthroughs in medicine, increase leisure time, speed the pace of education, help make businesses more profitable, improve communication, make transportation smoother, safer, and faster, help save energy and conserve other valuable natural resources, help reduce crime, control the costs of government, and extend explorations in outer space. Surely any technology that offers such significant benefits is worth studying! Our ancestors worked 80- to 100-hour weeks under generally poor working conditions; with tireless computerized robots providing food, clothing, and shelter, it may become possible for future generations to work one- or two-day work weeks or not to have to work at all. Today, if we want a fact we might have to spend hours or days tracking it down; in a few decades the vast majority of facts known to humankind may be accessible to us in seconds from our personal computers. Part One of this book introduces some fundamental computer concepts, presents an overview of personal computing, and gives a concise account of the evolution of the modern computer.

Chapter 1

The Information Revolution

Publisher Summary

Information revolution is a period of change that might prove as significant to the lives of people. Computer technology is at the root of this change, and continuing advancements in that technology seem to ensure that this revolution would touch the lives of people. Computers are unique machines; they help to extend the brain power. Computerized robots have been replacing blue-collar workers; they might soon be replacing white collar workers as well. Computers are merely devices that follow sets of instructions called computer programs, or software, that have been written by people called computer programmers. Computers offer many benefits, but there are also many dangers. They could help others invade one’s privacy or wage war. They might turn one into button pusher and cause massive unemployment. User-friendly systems can be easily used by untrained people. The key development that made personal computers possible was the invention of the microprocessor chip at Intel in 1971.

Outline

Introducing the Computer

The Benefits

The Dangers

Looking to the Future

An Introduction to Personal Computing

What Is a Personal Computer?

A Brief History of Personal Computing

Personal Computing Software Applications

Case Study 1-1: The IBM Personal Computer

Case Study 1-2: The Apple Macintosh

Choosing a Personal Computer

The Social Impact of Personal Computers

After reading this chapter you will understand:

1. What the Information Revolution is and how it is affecting our lives

2. Why it is important to study computers

3. Some of the key benefits and dangers of using computers

4. The most common personal computer applications

5. The IBM Personal Computer and the Apple Macintosh

Left: The New York Stock Exchange makes extensive use of computers to keep up with today’s huge trading volumes that sometimes reach 40 million shares per hour.

What networks of railroads, highways and canals were in another age, networks of telecommunications, information and computerization … are today.

Bruno Kreisky, Austrian Chancellor

We are reaching the stage where the problems we must solve are going to become insoluble without computers. I do not fear computers. I fear the lack of them.

Isaac Asimov

Introducing the Computer

We are in the midst of what is commonly called the Information Revolution, a period of change that may prove as significant to our lives as the Industrial Revolution was to our ancestors. Computer technology is at the root of this change, and continuing advancements in that technology seem to ensure that this revolution will touch all our lives. We can only begin to guess the effects of the Information Revolution, but we can be certain that living through the revolution in the 1980s and 1990s will be exciting and challenging.

The machines of the 1800s, which triggered the Industrial Revolution, helped workers extend their muscle power. Most machines assist us in this way. Cars, for example, let us travel farther in less time than we can by foot or horse; typewriters enable us to write with less strain than we can by hand. Computers, however, are unique machines in that they help us extend our brain power. Their capabilities make it possible for us to do in hours what might otherwise take days (such as projecting sales or balancing a budget) and to work other problems we probably could not otherwise handle. We can now manage our personal lives and business enterprises with the useful information computers generate, and we can have that information sooner than if we were to try to create it ourselves. Computers help us tackle difficult personal and business decisions with greater assurance that the consequences of the decisions have been carefully anticipated.

At the beginning of this century the most common occupation in the United States was farming; today it is information processing. Ours has become an information-based society, and we depend on computers to help us handle this information. Computers, unknown to the masses as recently as a decade ago, have now become a common fixture in many homes, classrooms, and small businesses. In the 1940s, computers were scarce. In the late 1980s computers will be in most homes and businesses, in automobiles, toys, and appliances.

Businesses are becoming so dependent on computers that in a few years it may be difficult to get a job as an office clerk without having some computer expertise. Computerized robots are already replacing blue-collar workers on assembly lines (Figure 1-1); eventually they may be able to replace white-collar workers as well. Students are being prepared for these changes. But what about people already in industry? Will they be able to adapt as their environments become more heavily computerized? As you will see throughout this book, the impact computers have and will have on society provokes many serious questions. You will be frequently asked to consider carefully the consequences of computer technology.

Figure 1-1 These computer-controlled robots weld car bodies ten times faster than humans and with much greater accuracy.

Within the next decade computers could become the world’s largest industry, displacing both the automobile and oil industries. It has been forecast that International Business Machines Corporation (IBM), one of the foremost manufacturers of computers, could become the world’s largest company by the year 2000.

Why are computers becoming so popular? Simply put, they are becoming financially accessible and both useful and attractive to more people. As recently as the late 1950s most computers filled entire rooms and cost hundreds of thousands, even millions, of dollars. Today microprocessors (Figure 1-2), tiny computers etched onto thin slivers of silicon called silicon chips, may be purchased for a few dollars apiece. There is every reason to believe that in a few years the cost of these microprocessors will be so negligible that computing will be almost free. Certainly this will dramatically change our lives.

Figure 1-2 The microprocessor chip shown here is as powerful as the room-size computers of a few decades ago.

People are coming into contact with computers daily. These machines, once thought mysterious, are now being used routinely as more and more people are beginning to realize that computers are merely devices that follow sets of instructions, called computer programs or software, that have been written by computer programmers.

People are finding that the instructions computers follow help to simplify their own lives. Programs may instruct a computer to perform such functions as totaling a store’s cash receipts or preparing a company’s payroll, customer statements, or tax returns. They may instruct a computer to perform such varied tasks as computing missile trajectories or controlling a robot arm to weld car bodies. They may instruct a traffic control computer when to change traffic lights or an air traffic control computer how to determine whether two planes are on a collision course.

The computer is down! Everybody think! ©Creative Computing

Many people would be surprised to discover that they already own several computers, most likely in the form of microprocessor chips embedded in digital clocks, digital watches, TV sets, home video games, microwave ovens, and automobiles. Home appliances already contain talking computers that warn if the washing machine is overloaded or the dishwasher needs more soap.

The power of the prohibitively expensive giant brains of a few years ago is now available in desktop personal computers (Figure 1-3) that cost only from a few hundred to a few thousand dollars. School systems are under tremendous pressure from parents and students alike to increase the use of personal computers and offer more computer courses. Small businesses are already finding it difficult to remain competitive without using computers to assist in such office procedures as preparing payroll, taking inventory, billing customers, and budgeting.

Figure 1-3 The IBM Personal Computer is one of the best-selling personal computer systems in the world.

Computers may also be instructed to assist in creating new products. The production and distribution of this textbook was itself highly computerized. The text was written on a word processor, and later typeset on a computerized photocomposition system. The photographs and color in the diagrams were processed and prepared with computerized laser-scanning systems (see Chapter 5). In marketing research for this book, computers were used to compile the results of a detailed survey of more than a thousand professors teaching introductory computer courses. Computers scanned lists of faculty members to determine which instructors might be interested in receiving examination copies of the text.

Computers have become so useful in so many areas of life that they have become indispensable to many people. Computers have become a part of our lives.

The Benefits

You may agree that computers are becoming a more important part of our lives but still wonder: Why invest a great deal of time and effort to consider this technology? Part of the answer is that computers are everywhere around us in our personal lives and in our business enterprises. They are one of the most significant technologies that will influence our future.

More importantly, studying how computers work will help you learn how they can help you extend your thought processes. If you want to reap the benefits of most other machines, you need only know how to operate them. You can benefit from a car by driving one, even if you don’t understand how it works. Computers operate differently, however. They are problem-solving tools. To benefit from a computer, you must be able to ask the right question about the problem and to manipulate the information correctly to reach an answer. To do that, you must understand the technology.

Once understood and programmed correctly, computers can be used to make life more convenient, more enjoyable, and more rewarding. They can enrich every facet of life. They are fun to use and can help reduce tedious work. They can be used to improve the lives of disadvantaged and handicapped people, facilitate major breakthroughs in medicine, increase leisure time, speed the pace of education, help make businesses more profitable, improve communication, make transportation smoother, safer, and faster, help save energy and conserve other valuable natural resources, help reduce crime, control the cost of government, and extend explorations in outer space. Surely any technology that offers such significant benefits is worth studying!

The Dangers

Although computers can help us improve the quality of our lives, many people consider them potentially dangerous. They fear that computers could be the greatest boon to those who would invade our privacy or wage war against us. Others wonder if computers will relegate us to pushing buttons, thus destroying the incentive to achieve. Some people fear that massive unemployment will result as machines displace workers. They wonder if our computer-controlled weapons of destruction will become so complex that we might lose control of them and cause an accidental nuclear war. Might a poorly designed computer system cause the life support system of an intensive care patient to fail? Will the personal touch disappear? Will society be divided into the computer-haves and the computer-have-nots? An understanding of computer logic will help to dispel many of these fears.

Looking to the Future

Despite the fear of computers some people have, most people are somehow involved in the Information Revolution and, therefore, with computers. Although the inflation of the 1970s and early 1980s hit many industries, the costs of computing have been decreasing rather than increasing—in fact, decreasing dramatically. Many people even delay purchasing computers because they hope that the prices will decline even further. Computing costs can be expected to decline to the point that we may soon be able to afford all the computer power we could possibly use, so that almost any imaginable application of computers may be attempted. Similarly, the costs of data communications will also continue declining as transmission capacities increase. Therefore, we will be able to transmit huge amounts of information between computers at great speed and nominal cost.

We can also expect the base of potential computer users and applications to continue to broaden, creating new computing careers and new benefits from computers. This extension of computer use is already evident in the growing interest in purchasing home computers. In fact, as people use computers successfully, they continue to give computers more to do. If computers malfunctioned regularly or if their costs were too high, people would avoid using them. But the experience with computers has been a positive one. It seems as though there is an applications spiral, with an ever-increasing range of applications being attempted.

Perhaps this growth in the number of users is a result of the important trend toward creating systems that are user-friendly (Figure 1-4), that is, systems that can be easily used by untrained people. The really big breakthroughs in this area will not come until the late 1980s and early 1990s. For example, personal computers may already be economical enough for many people to own, but they are still very unfriendly devices. Speech synthesis and speech recognition may help solve this problem as computers converse with their users in everyday English.

Figure 1-4 The help key is one of the most important keys on today’s computer keyboards. The user may press it at any time to receive useful information about how to proceed. Providing assistance in this manner makes computers more user-friendly.

Lastly, laser technology will greatly affect the course of computing over the next several decades. A laser is a device that creates an intense beam of monochromatic (one-color) light (Figure 1-5). The text contains many in-depth explanations of how the special properties of laser beams are used in today’s computers and data communications systems. It has been forecast that by the year 2000 today’s electronic computers will be replaced by laser-driven optical computers.

Figure 1-5 How a laser works.

Will the world be a better place as a result of the Information Revolution, or just a different place? Certainly it will be different. We can help ensure that it becomes a better place by carefully studying computers, examining the many controversial issues raised about them, and devoting careful thought to planning computer applications.

An Introduction to Personal Computing

The remainder of this chapter introduces the elements of personal computing. The term personal computer is defined, and a brief history of the field is presented. The most common personal computing applications are discussed, and the most popular types of personal computing software packages are listed. Case studies then introduce two of today’s most important personal computers, namely the IBM PC and Apple’s Macintosh. Since most people are likely to own their own personal computers eventually, a section on how to choose a personal computer is included. The chapter concludes with a discussion of important social issues raised by the widespread use of personal computing.

What Is a Personal Computer?

A personal computer is a complete computer system that is available for the personal use of one or more people at work or at home. It is generally small enough to fit on a desktop and economical enough to be affordable by an individual. It should be user-friendly, so that it can be used easily by people who are not computer specialists. It should be usable directly out of the box, reliable, and serviceable, and should have easy-to-read documentation. It should be able to run the huge variety of personal computing applications software available. Most personal computers are not portable, but many truly portable personal computers are available (Figure 1-6).

Figure 1-6 The EPSON HX-20 is a complete computer system weighing less than 4 pounds. It includes a printer, LCD screen, microcassette tape recorder/player, sound generator, and many other features. It runs for 50 hours on a rechargeable set of nickel cadmium batteries. Here the HX-20 is being used as a portable data communications terminal.

A Brief History of Personal Computing

The key development that made personal computers possible was the invention of the microprocessor chip at Intel Corporation in 1971.

In 1975 Steve Jobs, then 19 years old and a technician at Atari, and Steve Wozniak, an electronics engineer at Hewlett-Packard, decided to build a computer in Jobs’s parents’ home in Palo Alto, California. They bought a microprocessor chip for $25 and went to work on a machine they later called Apple. They brought their Apple to a computer hobby shop in Palo Alto. The shopkeeper was so impressed that he ordered 50 machines. Jobs sold his Volkswagen and Wozniak pawned his calculator—Apple Computer was born with $1300 in capital. The Apple II (Figure 1-7), Apple’s first widely marketed product, became the machine practically equated with the term personal computer.

Figure 1-7 The Apple II personal computer.

In 1977 Tandy Corporation marketed its first TRS-80 personal computer through its huge network of Radio Shack retail stores (Figure 1-8). Commodore, a company with expertise in marketing electronic calculators, entered the market with its PET computer.

Figure 1-8 The TRS-80 Model 1 was introduced by Radio Shack in 1977 for the then incredibly low price of $599. It used a cassette tape player for storing and retrieving programs and data.

It wasn’t until 1981 that IBM plunged in with its IBM Personal Computer and quickly became the world’s leading manufacturer of personal computers. Apple countered with the introduction of its extremely powerful and user-friendly Macintosh system. Case studies on the IBM Personal Computer and the Apple Macintosh follow the next section.

Personal Computing Software Applications

Personal computers may be used for an almost endless variety of applications. It is the software that enables a personal computer to perform each particular application. A great variety of software is available, but certain types of software packages are the most commonly used.

Word processing systems (Figure 1-9) are used by authors, students, and businesspeople to facilitate the creation and manipulation of text. Text is typed in and the computer stores it in its memory. Changes may then be made and a clean copy retyped at the touch of a button. If multiple copies are needed, possibly with minor changes, they can be produced much faster than by typing them individually.

Figure 1-9 Microsoft Word/word Processing program. (Microsoft is a registered trademark of Microsoft Corporation.)

Database management systems (Figure 1-10) facilitate the storing and retrieving of user information. People use database management software packages to organize household budgets, maintain Christmas lists, store inventories of household valuables for insurance purposes, maintain organization membership rolls, manage mailing lists, and prepare selective mailings.

Figure 1-10 Microsoft File/Data Management program.

Electronic spreadsheets (Figure 1-11) are used primarily in financial planning applications such as budgeting. Graphics packages (Figure 1-12) enable the user to prepare charts and graphs.

Figure 1-11 Microsoft® Multiplan® Electronic Worksheet program.

Figure 1-12 Microsoft Chart/Complete Business Graphics program.

Operating systems control the computer’s hardware and make it more convenient and accessible to the users. Programming language packages (Figure 1-13) enable users to write and debug their own programs. Data communications packages enable computers to communicate with one another.

Figure 1-13 Microsoft BASIC Interpreter.

We will soon be able to purchase expert systems software packages to provide us with expert advice on taxes, legal problems, first aid, and so on. The market for such software is large and virtually untapped at the present time.

Personal computers have been most useful in businesses, but home computers are becoming increasingly popular. In the home, computers are used for security, energy management, income tax preparation, game playing, telecommuting (working at home via computer terminals), shopping at home, home banking, stock portfolio management, education, and meal planning.

Case Study 1-1 The IBM Personal Computer

The IBM Personal Computer (Figure 1) was introduced in August 1981 and rapidly became the world’s most popular personal computer.

Figure 1 The key components of the IBM PC are: (a) system unit, (b) expansion unit, (c) keyboard, (d) color display, (e) printer.

The PC, as it is commonly called, features an Intel microprocessor chip (smaller than a penny) capable of performing more than 250,000 calculations per second.

The main hardware units on the IBM PC are the system unit, expansion unit, keyboard, display, and the printer. The system unit contains the system board (Figure 2) that houses the microprocessor, the user memory (random access memory or RAM), and the permanent memory (read only memory or ROM). User programs must first be placed in RAM before they can be executed (that is, performed) by the PC. The ROM contains a self-test program that automatically checks out key features of the PC each time it is turned on and instructions that help control functions such as the entering, displaying, and printing of information.

Figure 2 The system board (background) of the IBM PC. The smaller board in the foreground controls diskette drives.

The system unit also contains several expansion slots. They allow the user to add memory, displays, printers, communications devices, and an expansion unit as the user’s needs grow. The system unit has space for one or two diskette drives in which users may insert floppy disks containing the programs and data they wish to use at any time. Each floppy disk has a capacity of 180 Kb or 360 Kb (Kb means kilobyte, or approximately one thousand bytes; one byte is roughly equivalent to one character of information). It also houses a power supply and a speaker for music and voice applications.

The expansion unit provides a 10 Mb (Mb means megabyte, or approximately one million bytes) fixed disk drive, as well as several additional expansion slots. Storing and retrieving information on the fixed disk drive is much faster than with floppy disks. Also, many more applications can be kept on the fixed disk simultaneously, so that it is possible to switch quickly between applications and to integrate the outputs of separate applications. The 10 Mb fixed disk drive can hold the equivalent of more than 5000 pages of double-spaced typewritten text, an amount of information storage that is more than sufficient for most small businesses.

The IBM PC/XT (PC extended) model comes with a 10 Mb fixed disk drive, 128 Kb of user memory (double that of the PC), eight expansion slots, and a communications adaptor.

The PC has a detached keyboard for user convenience. The angle of the keyboard may be adjusted. The keyboard has both tactile (touch) and audio (sound) feedback; each of these features is designed for the comfort of users who enter a great deal of information at keyboards. At the right of the keyboard is a 10-key numeric pad, like that used on calculators, for rapid entry of numeric information (Figure 3). The PC contains a 15-character type-ahead buffer for fast typists; if the computer can’t digest the characters as quickly as they are typed, it at least saves